[Rd] Testing for a reference class object

John Chambers jmc at r-project.org
Thu Mar 10 18:47:29 CET 2011

There is a virtual class "refClass" that all reference classes subclass, 
so is(x, "refClass") is the natural test, as in:

 > foo <- setRefClass("foo", fields = "bar")
 > x <- foo$new()
 > is(x, "refClass")
[1] TRUE

On 3/10/11 7:40 AM, Jeffrey Horner wrote:
> Hi all,
> I've constructed the following function to test whether or not an
> object was created from a reference class:
> isRefClassObject<- function(x) isS4(x)&&
> is.environment(attr(x,'.xData'))&&
> exists('.refClassDef',attr(x,'.xData'))
> but I'm unsure if it's a complete test or if there's a better way to
> test. Regardless, It would be nice to have such a function in the
> methods package.
> I have a case where I'd like to ensure that an object is constructed
> from a reference class AND that it implements a certain method:
> if (isRefClassObject(x)&&  'run' %in% getRefClass(x)$methods())
>      x$run()
> Thanks,
> Jeff

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